Participants in this study exhibited different ability and skill profiles. The Cerebral Palsied population is a heterogeneous group with different physical and sensory impairments, different profiles in language and cognitive abilities, and varied educational experiences. Higginbotham and Bedrosian (1995) have stated the possession of some sort of communication disability and use of a communication technology may be their only commonalities. Therefore, there are difficulties in the implementation of group designs given the low incidence of the AAC population and the variability within this population (Bedrosian, 1999; Light, 1999; Sevcik, Romski and Adamson, 1999). However, despite this variety of personal circumstances, an effort was made to gather a sample as similar and numerous as possible. Though, we are conscious of the small sample in this study. Therefore, any generalization of our findings across persons that use AAC systems and our conclusions should be taken with caution.

In this study we assumed that working memory capacity and phonological skills would have an effect on reading and spelling performance in a group of people with CCN. A finding of this study was that, although the high working memory group scored higher in all literacy tasks than low working memory group, differences were only significant for the knowledge of orthographic patterns, for the reading of words, and for the spelling of pictures’ names. The second finding of this study was that differences on phonological skills were related to differences in the spelling of pseudowords and pictures' names, to differences in the number of letters spelled in words, and to differences in the spelling of the first and last letter in pseudowords; nevertheless, differences on phonological skills had no effect on all reading measures but in the reading of words.

As it is known, working memory is important for reading (Baddeley, 1982; Daneman and Carpenter, 1980). Memory is involved in learning the spelling conventions, too. In fact, for an expert reader, reading involves the recognition of words and their specific spellings. In Spanish, there is an important number of words that have specific spellings. In order to recognize these words and to read them for accessing their meanings, a person has to know the orthographic rules (i.e., words with same sounds [b-v, j-g, c-q-k, ll-y, h-no h] but conventional spellings). As our results show, it seems that, once orthographic knowledge is learned and a visual sight vocabulary is acquired, working memory has a role in reading performance. In our study, it was significantly easier for high working memory capacity participants to recognize written orthographic conventions and to read words than for low working memory capacity ones; in fact, the higher number of correctly recognized and read words for the former group, seems to suggest so. Obviously, their high cognitive capacity has allowed participants to significantly learn much more orthographic conventions and to succeed in recognizing a greater amount of orthographic patterns. In this sense, low working memory capacity participants have acquired a very restricted visual written vocabulary, and therefore they have stored in memory a fewer amount of visual representations of words; they have read significantly less visual words, and they have made a high number of mismatches between read words and pictures. These significant differences might be interpreted as an evident lack of success of low working memory participants in using the visual route in reading. Furthermore, though in this study we have not taken into account on-line reading measures, we have informally appreciated that it took longer for them to read the words. This fact could also be interpreted as an evidence of the use of the indirect route in reading, and as a failure in the application of the GPCR when using the phonological route in reading familiar words. Low working memory group read at a very basic level, they could not even read the fiftieth percent of the tested words; those words constitute a very basic visual vocabulary that was chosen from a reading test that typically applies to children from 6 to 9 years old in Spanish.

When looking at phonological skills groups' results in reading, significant differences were found in the reading of words but not in pseudoword reading. It was surprising because it was expected that high phonological skills group would outperform in this latter task. Participants were assigned to high phonological skills condition, precisely, because of their high capacity to solve phonological tasks. Phonological skills are basic in order to grasp the alphabetic principle (Gough, Ehri y Treiman 1992; Byrne and Fielding-Barnsley, 1990). Besides, in order to read pseudowords, for which there are not any representations in the lexicon, phonological skills are necessary as grapheme to phoneme correspondence rules must be applied (Morton, 1979b). Our results, though different to the expected ones, are similar to those reported in literature. Research has showed this same lack of ability of cerebral palsied preschool children in applying their demonstrated phonological skills in reading (Dahlgren Sandberg and Hjelmquist, 1996a, b). Expert readers characterize by their ability to indistinctly use the direct and the phonological routes in reading (Coltheart, 1978; Grainger and Ferrand, 1996). In this study, the high phonological skilled group behaved as a novice reading group, in that they could not rely on their phonological abilities in order to solve the pseudoword reading problem; nevertheless, they could solve the word reading problem significantly better than low PS group. This means their reliance on a well-known visual vocabulary but their difficulty to read new words using the indirect route. Looking for an explanation of the lack of significant differences between phonological skills groups, performance within groups was analyzed. It was noticed that some of the participants within the high phonological skills group did nearly perfect in the reading of pseudowords, meanwhile some other participants did not read half of the pseudowords. Maybe variability within groups has masked the real potential of phonological skills in reading. As a positive outcome, we should emphasize that all participants, regardless their high or low phonological skills condition, were able to decode pseudowords to a certain extent. However, when GPCR are incorrectly applied, there is no progress in reading and this might be the real situation for the low phonological skill group.

As it has been suggested, children may use, from the very first moment of systematic reading acquisition, the direct route in lexical access; supporting evidence comes from studies that show that frequent words are much better read than infrequent ones, and from studies were children read words more easily than pseudowords, showing the lexical category effect (Defior, Justicia and Martos, 1998; Domínguez and Cuetos, 1992). This is our participants’ situation. Words in Cuetos et al.’s reading test were very frequent Spanish words which may explain the significant better results in reading them with a whole-word strategy. This might be interpreted as Defior et al. (1998) suggested, as an indication of the advantage of using the visual or direct route as an aid in word reading. Moreover, the worse performance in both PA groups in pseudoword reading compared to word reading performance may be another indication of participants’ poor reading skills. This poor reading skills linked to the unsuccessful use of the phonological route turned participants into novice readers. It has also been remarked that previous automation in the use of grapheme to phoneme correspondences’ rules allows the development of orthographic representations (Defior, and al., 1998). Participants in this study, although were able to apply this rules to a certain extent as shown by correct percentages, have failed to automate this rules as they have not differed in orthographic patterns knowledge and in pseudoword reading. This is in line with literature’s reported findings about the difficulty of non speaking children to attain mastery of the grapheme-phoneme relationships necessary for successful word recognition and word identification (Dahlgren Sandberg and Hjelmquist, 1996b). Also, our results bring into line with Dahlgren Sandberg and Hjelmquist (1997) and Foley (1993). They stated that the normal model for development of literacy skills did not fit their results since the phonological skills of the participants in their study were not accompanied by the expected reading and writing level; so our participants were. However, Dahlgren Sandberg and Hjelmquist (1997) noticed that within the non speaking group, there was indication that reading and spelling were related to phonological skills. In our study this was evidenced by high PA group’s word reading significant results.

From a lexical processing point of view, it has been pointed out that a competent reader is that one who can efficiently use both, the visual and phonological routes to lexical access. It is accepted that both routes are potential and alternatively used, and that lexical and phonological processing interact (Coltheart, 1985). So, if a reader depends solely on one or the other route this could be interpreted as a symptom of difficulty or of poor reading skills (Rueda, 1995). In the case of our participants, the significant word reading differences found between phonological groups may be indicating a preferred visual word strategy, and conversely, absence of significant differences in pseudoword reading may indicate a failure in the application of correspondence’s rules. Goswami and Bryant (1990) have found that meanwhile phonemic awareness is of fundamental importance for spelling among young naturally speaking children, for early reading a whole-word strategy is at work, where the role of phonology is minimal. According to this statement, it could be said that high phonological skills participants used the visual reading strategy and as a group they could be labeled as early readers.

Regarding spelling results, it is important to note that, although there were no differences in the spelling of orally presented words and pseudowords between working memory capacity groups, both groups differed in the spelling of pictures’ names. It seems as if the verbal aid would have helped all participants to do the task. Words and pseudowords were spoken aloud by the examiner on an ongoing basis so that all participants could spell the items. Voiced presentations of words and pseudowords have played the role of an overt articulatory rehearsal of the phonological representations of the lexical items to the working memory. Taking into account both, the time that many participants spent selecting the letters and that this selection was made letter by letter, hearing aloud the words and pseudowords was an important clue. When low working memory capacity participants had to spell pictures’ names on their own, without any verbal assistance, they failed. Pictures’ names may be spelled either by generating a phonological representation, storing it, and then applying phonological skills or conversely, one may directly recuperate a visual orthographic pattern from the lexicon, which it is also a memory store. Significant high working memory results suggest that a bigger span or capacity allows a greater temporary store of such phonological information and more resources allocated to its processing. Another interpretation is that a higher memory capacity involves a greater amount of visual orthographic representations stored in it. Whatever route in spelling low working memory participants used, they failed to use it strategically. Taken together, the significant recognition of orthographic patterns in reading, the significant number of words read and this spelling result, we might speculate once again that high working memory group used the direct route in reading and spelling.

Lack of significance between working memory groups in the remaining spelling measures –total number of letters, first and last letters in all lexical items- is somewhat difficult to interpret. When individual performance profiles were examined it was found again a nearly perfect performance in some high working memory capacity participants, and very poor spelling results in some others. In fact, some high working memory capacity participants didn’t fail the spelling of any last letter neither in words, pseudowords or pictures’ names or they reached 100% correct in the spelling of total number of letters in words and in pictures’ name; on the contrary, some other high working memory participants couldn’t spell any last letter, and still there was one participant that couldn’t hardly spell 5% of the total amount of letters. Low working memory participants also had varied spelling performance profiles, from one participant that could spell all last letters and all first letters, and nearly all letters, to some other participants that were not able to spell either any first or last letter in any of the lexical elements. Thus, the high variability within memory groups might be involved in the lack of significance between working memory groups.

No significant differences were found between phonological skills groups in the spelling of words. As it is known, phonological skills may not be necessary in order to spell words, because words may be visually spelled or recuperated (Seidenberg, 1985; Taylor and Taylor, 1983). This fact might explain the absence of differences between high and low phonological skills groups. Phonological skills were not used for spelling the proposed words; participants needed not these skills for spelling because the lexical items were well known words, and they were spelled using the visual route –they were visual-graphemic recuperated according to Morton’s model (1979b). Therefore, neither high nor low participants used their phonological abilities for spelling, relying on the visual route for performing this task. On the contrary, phonological skills are absolutely necessary in order to spell pseudowords. In this sense, those persons with high phonological skills should succeed in this kind of spelling task; and this is another important finding in this study, namely, that phonological skill groups significantly differed in the spelling of pseudowords. This finding also indicates that phonological rules were not spontaneously but systematically applied; if low phonological skills participants had used them, differences would have been found in the spelling of pseudowords.

Phonological skill groups also differed in the spelling of pictures’ names. This significantly better result has to be jointly interpreted with words and pseudowords spelling results. High phonological skill group used the application of the PGCR for recuperating pictures’ names and spelling them; that is the reason why high phonological skill group outperform this task compared to low capacity group. When participants have a visual representation for the word, they may recuperate it as a whole; therefore, differences between phonological groups in the first task were not found, phonological skills were not needed for doing the task. When high phonological skill participants have not the visual representation either of the pseudoword or of the word depicted by the picture, they resort to the phoneme to grapheme correspondence rules in order to spell pseudowords and pictures’ names.

It has been argued that spelling depends on retrieval and reproduction of phoneme-grapheme relationships (Snowling and Stackhouse, 1983) and that phonemic awareness is of critical importance for spelling (Goswami and Bryant, 1990). The role of phonology was an important one in literacy performance in this study. High phonological group behaved as a skilled group in that they used a visual and also a phonological strategy for spelling, in contrast to reading. In this sense they were more expert in spelling compared to low phonological skill group. As Vandervelden (2003) has stressed phoneme awareness develops gradually as part of a developing skill in using the alphabetic principle in learning to read and write. The ability to use language sounds is a strongly associated ability to reading and spelling learning (Vandervelden and Siegel, 1995, 1996, 1997). Significant spelling results for high phonological skill group in the spelling of the first and last letters in pseudowords show an effect of phonological skills on spelling performance. As it was said before, for spelling pseudowords it is absolutely necessary to apply PGCR. Their higher level of phonemic awareness has allowed them to significantly spell a greater number of pseudowords. Lack of significance between phonological skill groups in the spelling of first and last letter in words and in picture’s names indicate that all subjects were able to use an early skill in spelling. These results coincide with Vandervelden and Siegel (1999, 2001) findings. Vandervelden and Siegel (1999, 2001) showed different amount of ability in the AAC students group in a spelling dictation task; their students exhibited a beginning level skill as they could spell the initial letter in a pseudoword; our participants showed a more advanced skill as they spelled the first and last letters in pseudowords, and finally, advanced skills were found as they could spell whole pseudowords. Our high PA group seems to show advanced skills compared to low phonological awareness ability group.

Concluding Remarks

This study, though descriptive, has thrown some light on the advantage that participants with high level of working memory capacity and participants with high level of phonological skills take on reading and spelling skills. Though significant, we wish to emphasize once again that our results should be taken with caution. First, we should say that this study was descriptive by nature and we can not make any inference about causal relationships among variables. Second, participants sample’s size was small and their learning histories, social environments, and language and abilities profiles were varied. What has been called the extrinsic variables in language and literacy learning (Smith and Blischak, (1997) might have had an influence in the results our participants reached. Another factor to be considered is that our study has involved Spanish language and as it is known this is a transparent language as opposed to opaque English language.

As a major conclusion it could be said that participants with a high level of working memory, as a group, have read and spelled basically using the visual route. A second major conclusion is that high phonological skills participants behaved in reading as novices, they read using the visual route; but for spelling they behaved as experts, they strategically used the phonological route for spelling pseudowords. These lexical elements can only be read using the indirect route, and in this task they outperformed compared to low phonological skills participants.

Educational and clinical implications are straightforward. When attending people with complex and special communication needs, working memory span should be trained, and phonological skills should also be programmed in the intervention or educational programs. As it has been found, memory has been involved in the recognition of a much greater amount of orthographic patterns and in the reading of a greater amount of visual vocabulary. Besides, as it has been stressed, conventional orthography allows communication without any restriction. If we want people with CCN to communicate using AAC devices based on traditional orthography, we should plan the practice of phonological skills in order to teach spelling skills later. We base this conclusion on the finding that literacy skills in the high phonological skills group were very much alike to those of expert writers of typical development. In this sense, Foley and Pollatsek (1999) have pointed out that many studies have demonstrated that when children who are weak in phonological awareness receive appropriate instruction, they improve much more rapidly in reading and spelling than do control groups, especially when this instruction is linked with letter-sound and word learning, and these gains are maintained for at least 2 to 4 years (Blachman, 1991, 1994; Blachman, Ball, Black and Tangel, 1994; Bradley, 1988; Lundberd and allies, 1988). That is also the case for children with complex communicative needs (Dahlgren Sandberg, 2001).

Further research is needed to elucidate whether the descriptive relations shown in this study have a causal nature or not. It would be necessary to carry out an experimental design to answer this question.

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